Stroboscopic tuning device for musical instruments

ABSTRACT

A stroboscopic tuning device for a stringed musical instrument that is mounted on the musical instrument adjacent to the strings to be tuned. A solid state circuit employs a frequency generator, such as a piezoelectric crystal oscillator or a tuning fork oscillator, to operate the stroboscopic light source at a preselected frequency. In the use of the device, a string is plucked, and when the vibratory motion of the plucked string is either the fundamental frequency or the harmonic frequency of the preselected operating frequency of the stroboscopic light source, the string will appear to an operator to be in a nonvibrating condition. At that time, the string is tuned or adjusted to the desired tone.

BACKGROUND OF THE INVENTION

The present invention relates in general to devices for tuning musicalinstruments and more particularly to a device for tuning stringedmusical instruments.

Heretofore, tuning devices operating on the principle of sympatheticvibrations and employing tuned reeds were mounted on the stringedinstrument for tuning the same. In this use of such a device, the stringon the instrument was plucked and the vibration of the tuning reed wasobserved. Such a device has been sold by Ed Sale Guitar Co. of Avon ByThe Sea, N.J., as the "Vu-Pitch" visual tuner. A visual tuner for astringed instrument employing a tuned reed and mounted on the stringedinstrument was disclosed in the U.S. Pat. to Musser, No. 3,421,402issued on Jan. 14, 1969, for Visual Tuner.

A solid state tuner has been sold by Continental Music, a division of C.G. Conn Ltd., as the "Strobotuner". The "Strobotuner", however, employedan indicator for showing the tuning condition and used a microphone topick up the frequency of a plucked string.

In the U.S. Pat. to England, No. 3,385,153, issued on May 28, 1968, forMethod Of Tuning Musical Instruments, a stroboscopic light source isspaced from the instrument to be tuned and is disposed in alignment tothe string of the musical instrument to be adjusted. The patent toEngland disclosed the employment of specially located frets to adjust tothe rate of the frame speed of a television receiver.

The U.S. Pat. to Shrady, No. 3,566,601, issued on Mar. 2, 1971, for aCrystal Oscillator Watch, discloses a piezoelectric crystal oscillator,the output of which is reduced by a dividing circuit. The output of thedividing circuit is connected to a drive circuit. A time-indicatingdevice is operated by the drive circuit. In the U.S. Pat. toBerlincourt, No. 3,764,848, issued on Oct. 9, 1973, for PiezoelectricStarter And Ballast For Gaseous Discharge Layers, a piezoelectricoscillator starts and operates a lamp.

In the U.S. Pat. to M. Hetzel, No. 2,971,323, issued Feb. 14, 1961, foran Electronically-Controlled Timepiece, and in the U.S. Pat. to Stendel,No. 3,743,960, issued on July 3, 1973, for Circuit For Driving FrequencyStandard Such As A Tuning Fork, a tuning fork is excited by electroniccircuits and transistorized electronic circuits.

SUMMARY OF THE INVENTION

A stroboscopic tuning device for a stringed musical instrument that issupported by the musical instrument.

A stroboscopic tuning device for a stringed instrument which employs acircuit including an oscillator to operate a stroboscopic light at aprecise frequency.

A stroboscopic tuning device for a stringed instrument which employs afrequency generator for exciting a circuit to operate a stroboscopiclight at a precise frequency.

A feature of the present invention is to provide a stroboscopic tuningdevice which is supported by a stringed instrument along the strings tobe tuned. When the resonating frequency of a plucked string is equal tothe frequency of the stroboscopic flicker or any harmonic thereof, thestring appears to an observer to be stationary or in a nonvibratingstate. When this occurs, the string so plucked is tuned to thestroboscopic frequency or an harmonic thereof. Each string of a stringedinstrument is generally desirably tuned either to the fundamentalfrequency or to a different harmonic of the fundamental frequency.

An object of the present invention is to provide a tuning device fortuning a stringed instrument that is accurate and durable and yet iseconomical to manufacture.

Another object of the present invention is to provide a tuning devicefor tuning a stringed instrument that is simple to use and also that isa visual-type tuner.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of a stroboscopic tuning device for a stringedinstrument embodying the present invention illustrated supported by thestrings of a stringed instrument.

FIG. 2 is a front elevation view of the stroboscopic tuning device shownin FIG. 1 illustrated mounted on the strings of a stringed instrument.

FIG. 3 is a side elevation view of the stroboscopic tuning device shownin FIGS. 1 and 2 illustrated mounted on the strings of a stringedinstrument.

FIG. 4 is a block diagram of an electrical circuit incorporated in thestroboscopic tuning device of the present invention.

FIG. 5 is a schematic and block diagram of a tuning fork piezoelectricoscillator employed in the electrical circuit illustrated in FIG. 4.

FIG. 6 is a schematic and block diagram of a subharmonic slaveoscillator employed in the electrical circuit illustrated in FIG. 4.

FIG. 7 is a schematic diagram of a drive circuit employed in theelectrical circuit illustrated in FIG. 4.

FIG. 8 is a schematic diagram of a modification of the drive circuitshown in FIG. 7.

FIG. 9 is a schematic diagram of a further modification of the drivecircuit shown in FIG. 7.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Illustrated in FIGS. 1-3 is a stroboscopic tuning device 20 for astringed musical instrument, which comprises a housing 21 havingsubstantially a rectanguloid configuration and made of suitablematerial, such as plastic. Formed in the housing 21 is a slotted opening25 which extends from a top wall 26 of the housing 21 through a bottomwall 27 of the housing 21. The slotted opening 25 also extends throughan end wall 28 of the housing 21. Formed in the bottom wall 27 is arecess 29, which extends into side walls 30 and 31 of the housing 21.

In the exemplary embodiment of the present invention, the stringedmusical instrument includes a plurality of strings E, A, D, G, B and E.As illustrated, the string B is the one under test and is observablethrough the slot 25. Thus, the bottom wall 32 of the housing 21 rests onthe strings E, A, D and G. Fixed to the housing 21 along the end wall 28are spaced string-engaging members 40 and 41, which serve to stabilizethe housing 21 through engagement with a string, such as the illustratedstring E. When it is desired to have the string G, for example, undertest, then the string G would be observed through the slot 25 and thestring-engaging members 40 and 41 would engage the string B. To test thestrings, such as E and A, for example, it is apparent that the housing21 can be supported by the musical instrument in an opposite transversedirection.

Projecting from a side wall 42 of the body 21 is a suitable leg 45formed with a threaded opening 46 therein. Received by the opening 46 inthreaded engagement with the surrounding wall thereof is a threaded post47 having at the free end thereof a base 48. The base 48 engages the topof the stringed instrument. Thus, by rotating the base 48 with thethreaded post 47, the height of the body 21 above the top of thestringed instrument can be adjusted so that the bottom wall 27 of thebody 21 rests firmly on certain strings of the musical instrument tostabilize the mounting of the body 21 on the stringed instrument.

Fixed to the side wall 42 in abutting relation with the leg 45 is asuitable lamp holder 50, which is made of suitable insulated orinsulating material, such as plastic. Mounted on the free end of thelamp holder 50 is a suitable stroboscopic light source 55, such as aneon light, light emitting diode, a gas discharge lamp or the like.Mounted in the body 21 is a suitable case or package containingelectronic circuitry 65 for exciting the stroboscopic source of light 55at a predetermined fundamental frequency over suitable conductors 66.

The present invention locates the source of stroboscopic light 55 belowthe strings or strings to be tested. Toward this end, the housing 21 mayrest upon or be supported by the body of the stringed instrument withmeans extending therefrom to locate the stroboscopic source of light 55below the string or strings to be tested. It is contemplated thatmirrors can be employed for reflecting light from below the stringswhile the source of light may be physically located above the strings.Mirrors can also be employed for changing the viewing angle of thestrings.

In the preferred embodiment of the present invention, the circuit 65comprises a frequency generator 70, which is a piezoelectric tuning forkor bar oscillator (FIG. 5). It is to be understood that well-known andconventional precision-tuned oscillators can be employed, such aspiezoelectric crystal oscillators and an R-C tuned oscillator.

The piezoelectric tuning fork oscillator 70 comprises a piezoelectrictuning fork 71 (FIG. 5) of the type sold by Seiko Instruments, Inc. ofTorrance, Calif., as Type SL-NST 660. The tuning fork or bar 71 servesas a resonator. The mechanical vibrations of the tuning fork or bar 71are coupled for electromechanical conversion through an R-C circuitcomprising resistors 72 and 73 and capacitor 74. The R-C couplingcircuit 72-74 is connected to a well-known monolithic timing circuit 75of the type manufactured by Motorola Semiconductor of Phoenix, Arizona,as the MC 1455. The monolithic timing circuit 75 comprises a suitabletransistor 76 which has its input electrode connected to the output sideof the R-C coupling circuit 72-74 and which has its base electrodeconnected to the input sides of an output buffer 77 and a flip-flopcircuit 78. Comparator circuits 80 and 81 are connected to the R-Ccoupling circuit 72-74 and to the flip-flop circuit 78.

The timing circuit 75 operates at a free running frequency. When thefree running frequency of the timing circuit 75 is close to the naturalfrequency of the tuning fork or bar 71, the timing circuit 75 oscillatesat the frequency of the tuning fork or bar 71 through the piezoelectriceffect thereof.

The output of the frequency generator 70 is conducted over a conductor84 to a suitable divider circuit 85. In the exemplary embodiment, thedivider circuit 85 is a subharmonic slave oscillator. Other suitabledividers, such as digital electronic dividers, subharmonic oscillatorsand the like may be employed equally as well. It is within thecontemplation of the present invention that the frequency of thefrequency generator 70 may be low enough so as to obviate the need of adivider circuit.

The divider circuit 85 (FIG. 6) comprises an R-C coupling network havingresistors 86 and 87 and a capacitor 88 for tuning the free runningfrequency. Connected to the R-C network 86-88 is an input electrode of atransistor 90. The base electrode of the transistor 90 is connected tothe output side of a flip-flop circuit 91 and a load 92. Comparatorcircuits 93 and 94 are connected at the input sides thereof to the R-Cnetwork 86-88 and at the output sides thereof to the flip-flop circuit91. Connected to another input side of the comparator circuits 93 and 94is a suitable master oscillator signal coupling diode 95.

The free running frequency oscillations tuned by the R-C circuit 86-88in FIG. 6 is higher than a subharmonic frequency of the fundamentalfrequency of the generator 70. This frequency is lowered when a diode 95conducts, causing the comparator circuit 93 input level over a conductor97 to be raised from voltage 2/3E to voltage E. This action causes thefree running frequency fed to an output buffer 92 to be reduced belowthe subharmonic frequency of the fundamental frequency of the generator70. The frequency applied to the output buffer 92 is locked to thesubharmonic frequency of the fundamental frequency of the generator 70before the end of a cycle because the voltage 2/3E input signal appliedto the comparator 93 is exceeded when the diode 95 stops conducting. Thediode 95 stops conducting when the voltage over conductor 84 is 2/3E andstarts conducting when the voltage over conductor 84 exceeds 2/3E.

The output of the divider circuit 85 is fed to a suitable light drivercircuit 99 over the conductor 96. Suitable light divider circuits arewell-known triggered blocking oscillator circuit (FIG. 7), inductivedischarge circuit (FIG. 8) and a transistor direct drive circuit (FIG.9). The blocking oscillator 99 (FIG. 7) comprises a transistor 100, thebase of which has the output of the divider circuit 85 applied theretoover the conductor 96. The emitter electrode of the transistor 100 is atground and the collector electrode of the transistor 100 has voltage Eapplied thereto through a transformer 101 which provides a regenerativefeedback to the base electrode through a dc blocking diode 102. Thesource of stroboscopic light 55 in the preferred embodiment is a neonlight, which is excited by the output of the transistor 100.

A modification of the drive circuit 99 is shown in FIG. 8 in the form ofinductive discharge circuit 99'. The inductive discharge circuit 99'includes a transistor 105 having the output of the divider circuitapplied to the base thereof over the conductor 96. The emitter electrodeof the transistor 105 is at ground and the collector electrode of thetransistor 100 has the voltage E applied thereto through an inductor106. The source of stroboscopic light 55, in the form of a neon light,is connected to the collector electrode of the transistor 105 to beexcited by the output thereof.

A further modification of the drive circuit 99 is shown in FIG. 9 as atransistor direct drive circuit which comprises a transistor 110. Thebase electrode of the transistor has the output signal from the voltagedivider circuit 85 applied thereto over the conductor 96. The emitterelectrode of the transistor 110 is at ground and the collector electrodeof the transistor 110 has the source of stroboscopic light, such as theneon light 55, connected thereto as the load. The source of stroboscopiclight 55 is excited by the output of the transistor 110.

On a conventional guitar there are six strings, namely: E, A, D, G, Band E. The desired frequencies for the strings E, A, D, G, B and E,respectively, are 82.5 cps, 110 cps, 146.666 cps, 195.555 cps, 247.5cps, and 330 cps. In the preferred embodiment of the present invention,the source of stroboscopic light 55 flickers at a frequency of 27.5 cps.The desired frequencies of the strings E, A, B and E are harmonics ofthe stroboscopic frequency of 27.5 cps. Each string is tunedindividually. A string under test is activated, the vibratory actionappears stationary or nonvibratory against the stroboscopic light source55 when the string is properly tuned or adjusted to the desiredfrequency. The D and G strings are tuned by fretting to the E and Astrings respectively. Thus, only a single stroboscopic frequency isrequired. However, means for tuning to various frequencies is within thepurview of the present invention.

I claim:
 1. A tuning device for a stringed instrument comprising:a. asource of stroboscopic light; b. means adapted to be supported by thestringed instrument in juxtaposed relation with the strings of saidstringed instrument, said source of stroboscopic light being mounted onsaid means for supporting said source of stroboscopic light adjacent thestrings of the stringed instrument; and c. circuit means connected tosaid source of stroboscopic light for exciting said stroboscopic lightat a preselected frequency.
 2. A tuning device as claimed in claim 1wherein said means comprises a housing and said circuit means beingdisposed in said housing.
 3. A tuning device as claimed in claim 2wherein said means includes a member supported by said housing and onwhich said source of stroboscopic light is mounted to be disposed belowthe strings of the stringed instrument and said housing is disposedabove the strings of the stringed instrument in contact with strings ofthe stringed instrument to be supported thereby and said housing beingformed to be in spaced relation with at least one of said strings of thestringed instrument and said housing being formed with an openingtherein through which at least said one string is observable.
 4. Atuning device as claimed in claim 1 wherein said means includes a membersupported by said housing and on which said source of stroboscopic lightis mounted to be disposed below the strings of the stringed instrumentand said housing is disposed above the strings of the stringedinstrument in contact with strings of the stringed instrument to besupported thereby and said housing being formed to be in spaced relationwith at least one of the strings of the stringed instrument and saidhousing being formed with an opening through which at least said onestring is observable.
 5. A tuning device as claimed in claim 1 whereinsaid circuit comprises a frequency generator for exciting said source ofstroboscopic light at the preselected frequency.
 6. A tuning device asclaimed in claim 5 wherein said frequency generator is a piezoelectricoscillator.
 7. A tuning device as claimed in claim 5 wherein saidcircuit comprises a light driver circuit for operating said source ofstroboscopic light in response to excitation by said frequencygenerator.
 8. A tuning device as claimed in claim 7 wherein said circuitcomprises a divider circuit connected to the output of said frequencygenerator and the input of said light driver circuit.
 9. A tuning deviceas claimed in claim 3 and comprising a string-engaging member on saidhousing for engaging a string of the stringed instrument other than saidone string for stabilizing said housing.
 10. A tuning device as claimedin claim 4 and comprising a string-engaging member on said housing forengaging a string of the stringed instrument other than said one stringfor stabilizing said housing.
 11. A tuning device as claimed in claim 2wherein said means includes a member supported by said housing and onwhich said source of stroboscopic light is mounted to be disposed belowthe strings of the stringed instrument.
 12. A tuning device as claimedin claim 1 wherein said means includes a member supported by saidhousing and on which said source of stroboscopic light is mounted to bedisposed below the strings of the stringed instrument.